WASHINGTON — Tethers Unlimited is designing a satellite servicing vehicle that would leverage technologies developed for the U.S. Defense Department and NASA to service spacecraft in low Earth orbit. Tethers Unlimited already has many of the technologies needed for the servicer either completed or in development under Small Business Innovation Research (SBIR) grants, CEO Robert Hoyt told SpaceNews. By combining these technologies, the company hopes to have a servicer called LEO Knight in orbit within three to four years, he said. The servicer would support on-orbit assembly, refueling for small satellites and other functions, he said. Tethers Unlimited is focusing on the small satellite market in low Earth orbit, targeting spacecraft too small to be economically serviced by robotic spacecraft like the one being developed under the U.S. Defense Advanced Research Agency’s Robotic Servicing of Geosynchronous Satellites (RSGS) program, Hoyt said. A 100-kilogram LEO Knight servicer would weigh 180 kilograms fueled, he said. “Its smaller size and lower cost will make it economically viable for missions such as refueling small, low-altitude satellites, removing derelict smallsats from constellation altitudes, assembling ESPA [EELV Secondary Payload Adapter] payloads to create persistent space platforms, and delivering and integrating payloads onto ...